7.2 Quick Help Customization

Ediff provides quick help using its control panel window. Since this window
takes a fair share of the screen real estate, you can toggle it off by
typing ?. The control window will then shrink to just one line and a
mode line, displaying a short help message.

The variable ediff-use-long-help-message tells Ediff whether
you use the short message or the long one. By default, it
is set to nil, meaning that the short message is used.
Set this to t, if you want Ediff to use the long
message by default. This property can always be changed interactively, by
typing ? into Ediff Control Buffer.

If you want to change the appearance of the help message on a per-buffer
basis, you must use ediff-startup-hook to change the value of
the variable ediff-help-message, which is local to
ediff-control-buffer.